Scribing method, cutter wheel, scribing device using the cutter wheel, and cutter wheel manufacturing device for manufacturing the cutter wheel

ABSTRACT

In a glass cutter wheel where a blade edge is formed on a disk-shaped wheel, grooves having a predetermined shape are formed at a predetermined pitch in a ¼ or smaller or ¾ or smaller blade edge line portion of the entire perimeter of the blade edge. The ratio of the groove portion to the entire perimeter, which largely contributes to a scribing characteristic, is changed such that a desired scribing characteristic can be obtained.

TECHNICAL FIELD

[0001] The present invention relates to: a scribing method of forming ascribe line for separating a brittle material; a cutter wheel, which isa scribe cutter used for forming a scribe line in a brittle material; ascribing apparatus incorporating such a cutter wheel; and a cutter wheelproduction apparatus for producing such a cutter wheel.

[0002] The brittle material includes glass, used for a glass substrateor a bonded glass substrate, a semiconductor wafer, ceramics, etc.

BACKGROUND ART

[0003] FIGS. 1(a) through 1(d) are cross-sectional views forillustrating a first separation method of a liquid crystal mothersubstrate in a step-by-step manner as an example of a conventionalprocedure for cutting a bonded glass substrate, such as a liquid crystalmother substrate, at a desired cutting position. In the followingdescriptions, in a bonded glass substrate formed by a pair of glasssubstrates, which is a liquid crystal mother substrate, one of the glasssubstrates is referred to as an A-side glass substrate, and the otherglass substrate is referred to as a B-side glass substrate, forconvenience of explanation.

[0004] (1) First, as shown in FIG. 1(a), the bonded glass substrate 1 isplaced on a first scribing apparatus such that the A-side glasssubstrate is laid over the B-side glass substrate, and the A-side glasssubstrate is scribed using a glass cutter wheel 2 so as to form a scribeline Sa.

[0005] (2) Next, the bonded glass substrate 1 in which the scribe lineSa was formed in the A-side glass substrate is turned over, andtransported to a second scribing apparatus. In this second scribingapparatus, the B-side glass substrate of the bonded glass substrate 1 isscribed using a glass cutter wheel 2 so as to form a scribe line Sbwhich is parallel to the scribe line Sa as shown in FIG. 1(b). It shouldbe herein noted that, in the case of a liquid crystal mother substrate,a plurality of liquid crystal panels are formed from the liquid crystalmother substrate, and in each liquid crystal panel, it is necessary toform terminals at a side edge portion in one glass substrate. Thus, inmany cases, the scribing position of the scribe line Sa formed in theA-side glass substrate and the scribing position of the scribe line Sbformed in the B-side glass substrate are shifted from each other along ahorizontal direction as shown in FIG. 1(b).

[0006] (3) Next, the bonded glass substrate 1 where the scribe lines Saand Sb were formed in the A-side glass substrate and the B-side glasssubstrate, respectively, is transported to a first breaking apparatuswithout being turned over, i.e., without exchanging the positions of theA-side glass substrate and the B-side glass substrate. In the firstbreaking apparatus, as shown in FIG. 1(c), the bonded glass substrate 1is placed on a mat 4. A break bar 3 is pushed against the B-side glasssubstrate of the bonded glass substrate 1 along the scribe line Saformed in the A-side glass substrate. As a result, a crack extendsupwardly from the scribe line Sa, and accordingly, the lower A-sideglass substrate is broken along the scribe line Sa.

[0007] (4) Next, the bonded glass substrate 1 in which the A-side glasssubstrate was broken is turned over such that the A-side glass substrateis over the B-side glass substrate, and transported to a second breakingapparatus. In the second breaking apparatus, as shown in FIG. 1(d), thebonded glass substrate 1 is placed on a mat 4. A break bar 3 is pushedagainst the A-side glass substrate of the bonded glass substrate 1 alongthe scribe line Sb formed in the B-side glass substrate. As a result,the lower B-side glass substrate is broken along the scribe line Sb.

[0008] By performing above steps (1) through (4), the bonded glasssubstrate 1 is separated into two at desired positions.

[0009] As illustrated in above steps (3) and (4), the break bar 3 ispushed against the upper glass substrate, whereby the lower glasssubstrate is broken. For example, as shown in FIG. 1(c), when the breakbar 3 is pushed against the upper B-side glass substrate, the A-sideglass substrate and the B-side glass substrate are bent downward at aposition against which the break bar 3 is pushed, whereby force isapplied to the A-side glass substrate so as to horizontally widen thecrack formed along the vertical direction (vertical crack) of the scribeline Sa formed in the A-side glass substrate. As a result, the verticalcrack extends upwardly so as to reach the upper surface of the A-sideglass substrate, whereby the A-side glass substrate is separated. On theother hand, in the scribe line Sb formed in the upper B-side glasssubstrate, force in a horizontal direction from both ends of the B-sideglass substrate toward the crack, which is the opposite direction tothat of the force caused in the lower glass substrate, is applied so asto compress the crack (vertical crack). Therefore, the B-side glasssubstrate is not broken.

[0010] In the breaking steps performed at steps (3) and (4), when thevertical crack of the scribe line Sa of the lower A-side glass substrateis shallow as shown in FIG. 1(c), it is necessary to apply a relativelylarge pushing force in order to break the A-side glass substrate.However, when the pushing force applied by the break bar 3 is toostrong, the upper B-side glass substrate may be broken simultaneouslywith the A-side glass substrate. In this case, in the lower A-side glasssubstrate, the vertical crack extends along a substantially verticaldirection to break the lower A-side glass substrate, i.e., no problem iscaused. However, since in the upper B-side glass substrate, the positionwhere the force is applied by the break bar 3 is different from theposition of the scribe line Sb formed in the B-side glass substrate,force is not caused in a direction such that the upper B-side glasssubstrate is broken. Thus, a separation face may be formed in an obliquedirection. Furthermore, cracks may be formed so as to be in contact witheach other so that defects (horizontal cracks) are caused at thatposition of contact. A bonded glass substrate having such a separationface extending along an oblique direction, or such defects, has nocommercial value as a liquid crystal panel.

[0011] The applicant of the present application has proposed aseparation method of a brittle substrate which can solve such problemsin Japanese Laid-Open Publication No. 6-48755 entitled “SeparationMethod of Bonded Glass Substrate”.

[0012] FIGS. 2(a) through 2(d) are cross-sectional views whichillustrate a second separation method for separating a brittle material,which is described in the above publication, in a step-by-step manner.Hereinafter, the method described in this publication is described withreference to FIGS. 2(a) through 2(d). In the following descriptionsalso, as referred to in FIGS. 1(a) through 1(d), in a bonded glasssubstrate formed by a pair of glass substrates, which is a liquidcrystal mother substrate, one of the glass substrates is referred to asan A-side glass substrate, and the other glass substrate is referred toas a B-side glass substrate, for convenience of explanation.

[0013] (1) First, as shown in FIG. 2(a), the bonded glass substrate 1 isplaced on a first scribing apparatus such that the A-side glasssubstrate is over the B-side glass substrate, and the A-side glasssubstrate is scribed using a glass cutter wheel 2 so as to form a scribeline Sa.

[0014] (2) Next, the bonded glass substrate 1 where the scribe line Sawas formed in the A-side glass substrate is turned over, and transportedto a first breaking apparatus. In this first breaking apparatus, asshown in FIG. 2(b), the bonded glass substrate 1 is placed on a mat 4. Abreak bar 3 is pushed against the B-side glass substrate of the bondedglass substrate 1 along the scribe line Sa formed in the A-side glasssubstrate. As a result, in the lower A-side glass substrate, a crackextends upwardly from the scribe line Sa, and accordingly, the A-sideglass substrate is broken along the scribe line Sa.

[0015] (3) Next, the bonded glass substrate 1 where the A-side glasssubstrate was broken is transported to a second scribing apparatuswithout being turned over, i.e., without exchanging the positions of theA-side glass substrate and the B-side glass substrate. In this secondscribing apparatus, the B-side glass substrate of the bonded glasssubstrate 1 is scribed using a glass cutter wheel 2 so as to form ascribe line Sb which is parallel to the scribe line Sa as shown in FIG.2(c). It should be herein noted that, in the case of a liquid crystalmother substrate, a plurality of liquid crystal panels are formed fromthe liquid crystal mother substrate, and in each liquid crystal panel,it is necessary to form terminals at a side edge portion in one glasssubstrate. Thus, in many cases, the scribing position of the scribe lineSa formed in the A-side glass substrate and the scribing position of thescribe line Sb formed in the B-side glass substrate are shifted fromeach other along a horizontal direction.

[0016] (4) Next, the bonded glass substrate 1 is turned over such thatthe A-side glass substrate is over the B-side glass substrate, andtransported to a second breaking apparatus. In the second breakingapparatus, as shown in FIG. 2(d), the bonded glass substrate 1 is placedon a mat 4. A break bar 3 is pushed against a portion of the A-sideglass substrate of the bonded glass substrate 1 which corresponds to thescribe line Sb formed in the B-side glass substrate. As a result, thelower B-side glass substrate is broken along the scribe line Sb.

[0017] By performing above steps (1) through (4), the bonded glasssubstrate 1 is separated into two at desired positions.

[0018] In this second separation method of a brittle material, asillustrated in steps (2) and (4), at a breaking step, the lower glasssubstrate to be broken has a scribe line whereas the upper glasssubstrate to does not have a scribe line. Thus, the upper glasssubstrate is not broken simultaneously with the breakage of the lowerglass substrate. Therefore, occurrence of the problems which may occurin the first separation method illustrated in FIGS. 1(a) through 1(d),such as a separation face extending along an oblique direction,formation of defects, etc., can be avoided.

[0019]FIG. 3 is a side view of the glass cutter wheel 2 used in thefirst and second separation methods, which is seen along a directionperpendicular to the rotation axis of the glass cutter wheel 2. Theglass cutter wheel 2 is formed into the shape of a disk, where φ denotesthe wheel diameter and w denotes the wheel thickness, and a blade edgehaving a blade edge angle α is formed along the perimeter of the wheel.

[0020] The applicant of the present application further improved theglass cutter wheel 2 shown in FIG. 3 to obtain a glass cutter wheelwhich can form a deeper vertical crack, which is disclosed in JapaneseLaid-Open Publication No. 9-188534 entitled “Glass Cutter Wheel”.

[0021]FIG. 4 is a side view of a glass cutter wheel disclosed in thispublication, which is seen along the rotation axis of the glass cutterwheel.

[0022] This glass cutter wheel 5 has undulations at the edge lineportion of a blade edge formed at the perimeter of a wheel. That is,U-shaped or V-shaped grooves 5 b are formed at the edge line portion 5 aof the blade edge. These grooves 5 b are formed by cutting notches atdepth h from the edge line portion 5 a at pitch P. By forming thesegrooves 5 b, protrusions j having a height h are formed at pitch P.

[0023] In FIG. 4, the grooves formed at the edge line portion are shownin a large size for the purpose of readily recognizing the grooves.However, the actual size of the grooves is a size of the micron order,which is not perceptible by a human eye.

[0024] TABLE 1 below shows specific numerical values of the wheeldiameter φ, the wheel thickness w, etc. The values are shown for twoexamples, Type 1 and Type 2. TABLE 1 Type 1 Type 2 Wheel diameter φ 2.5mm 2.0 mm Wheel thickness w 0.65 mm 0.65 mm Blade edge angle α 125° 125°Number of protrusions j 125 110 Height h of protrusions j 5 μm 10 μmPitch P 63 μm 63 μm Blade edge load 3.6 Kgf 1.8 Kgf Scribing speed 300mm/sec 400 mm/sec

[0025] The glass cutter wheel having undulations at the edge lineportion has a significantly improved scribing characteristic, i.e., asignificantly improved ability to form a vertical crack. By performing ascribing process using this glass cutter wheel, a deep vertical crackwhich almost reaches the vicinity of the lower surface of a scribedglass plate can be obtained in the scribing process.

[0026] The glass cutter wheel 5 having undulations at the edge lineportion has a significantly improved scribing characteristic as comparedwith a conventional glass cutter wheel. However, since preciseundulations are formed along the entire perimeter of the edge lineportion of the glass cutter wheel 5, the process and formation of theundulations in the edge line portion requires a long process time, andthere are some problems in processibility.

[0027] In the case where the second separation method illustrated inFIG. 2 is performed using the glass cutter wheel 5 having undulations atthe edge line portion, a scribe line Sb of a deep vertical crack isformed in the B-side glass substrate, and in some cases, the bondedglass substrate 1 is substantially separated at the time when the upperB-side glass substrate has been scribed at Step (3). Thus, when thebonded glass substrate 1 is transported using a suction pad, or thelike, to the second breaking apparatus during a transition periodbetween Step (3) and Step (4), one piece of the separated bonded glasssubstrate 1 may be left in the second scribing apparatus. Furthermore,during transportation of the bonded glass substrate 1, one piece of theseparated bonded glass substrate 1 may fall from the suction pad. Insuch a case, a production line apparatus for separating the bonded glasssubstrate 1 may not operate in a normal manner.

[0028] The present invention was conceived to solve the above problems.An object of the present invention is to provide: a glass cutter wheelwhere problems in processibility, which may occur in a glass cutterwheel having undulations in the entire perimeter of the edge lineportion, are solved, and a desired scribing characteristic can beobtained, i.e., a scribe line of a vertical crack having a desired depthcan be formed in a glass substrate separation process; a scribing methodfor forming a scribe line which enables separation of a brittlematerial; a scribing apparatus incorporating such a cutter wheel; and acutter wheel production apparatus for producing such a cutter wheel.

DISCLOSURE OF THE INVENTION

[0029] A scribing method of the present invention which uses a brittlematerial separation disk-shaped wheel having a central portion in athickness direction protruding in a circumferential direction so as toform a blade edge at an edge line portion of the wheel, and a pluralityof grooves having a predetermined shape formed in the edge line portionat a predetermined pitch, is characterized in that scribing is performedusing a wheel where the ratio of a length of a region occupied by theplurality of grooves with respect to an entire perimeter of the edgeline portion is smaller than 1, whereby a depth of a vertical crackformed inside a scribed brittle material is periodically varied.

[0030] In the above scribing method of the present invention, it ispreferable that scribing is performed using a wheel where the ratio of alength of a region occupied by the plurality of grooves with respect tothe entire perimeter of the edge line portion is equal to or smallerthan ¾.

[0031] In the above scribing method of the present invention, it is morepreferable that scribing is performed using a wheel where the ratio of alength of a region occupied by the plurality of grooves with respect tothe entire perimeter of the edge line portion is equal to or smallerthan ¼.

[0032] A cutter wheel of the present invention which is used forseparating a brittle material, where a blade edge is formed in an edgeline portion of a disk-shaped wheel, and a plurality of grooves having apredetermined shape are formed in the edge line portion at apredetermined pitch, is characterized in that the ratio of a length of aregion occupied by the plurality of grooves with respect to an entireperimeter of the edge line portion is smaller than 1.

[0033] In the above cutter wheel of the present invention, it ispreferable that the ratio of a length of a region occupied by theplurality of grooves with respect to the entire perimeter of the edgeline portion is greater than ¼, and equal to or smaller than ¾.

[0034] In the above cutter wheel of the present invention, it is morepreferable that the ratio of a length of a region occupied by theplurality of grooves with respect to the entire perimeter of the edgeline portion is equal to or smaller than ¼.

[0035] In the above cutter wheel of the present invention, it ispreferable that the pitch at which the plurality of grooves are formedis 20-200 μm according to a wheel diameter of 1-20 mm.

[0036] In the above cutter wheel of the present invention, it is morepreferable that the depth of the plurality of grooves is 2-200 μmaccording to a wheel diameter of 1-20 mm.

[0037] In the above cutter wheel of the present invention, it is morepreferable that the cutter wheel is integrally formed with a shaft whichpenetrates through the wheel.

[0038] In the above cutter wheel of the present invention, it is morepreferable that at least one groove region is formed in the edge lineportion; and the grooves have different depths such that the depth ofthe groove is deeper in a central portion of the groove region than inend portions of the groove region.

[0039] Another cutter wheel of the present invention is characterized inthat: groove regions are formed over the entire perimeter of the edgeline portion; and a region where the depth of the grooves becomesdeeper, and a region where the depth of the grooves becomes shallower,are continuously provided.

[0040] A scribing apparatus of the present invention which includes amechanism for moving a cutter head along the X-direction and/or theY-direction with respect to a table on which a brittle material isplaced, is characterized in that the cutter head is provided with theabove cutter wheel of the present invention.

[0041] A method for separating a bonded glass substrate of the presentinvention which includes a first scribing step, a second scribing step,and a breaking step, is characterized in that the above glass cutterwheel of the present invention is used in the second scribing step.

[0042] A method for separating a bonded glass substrate of the presentinvention which includes a first scribing step, a first breaking step, asecond scribing step, and a second breaking step, is characterized inthat the above glass cutter wheel of the present invention is used inthe second scribing step.

[0043] A cutter wheel production apparatus for producing the cutterwheel of the present invention, which includes: at least one rotatablysupported disk-shaped grinding member; and a grinding mechanism whichsupports at least one cutter wheel to be ground, and which advances andretracts the cutter wheel toward/from the grinding member, ischaracterized in that the grinding mechanism has rotation means formoving a portion of the cutter wheel which is to be ground by thegrinding member.

[0044] The above cutter wheel production apparatus of the presentinvention preferably further includes: advancing/retracting means foradvancing/retracting the grinding mechanism toward/from the grindingmember; and control means for controlling the advancing/retracting meansand the rotation means.

[0045] In the above cutter wheel production apparatus of the presentinvention, it is preferable that the control means controls the rotationmeans based on the number of divisions and the number of regions overthe entire perimeter of an edge line portion of the cutter wheel, so asto form a groove at a desired position in the edge line portion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0046]FIG. 1 illustrates a conventional separation procedure of a bondedglass panel.

[0047]FIG. 2 illustrates another conventional separation procedure of abonded glass panel.

[0048]FIG. 3 is a front view of a glass cutter wheel.

[0049]FIG. 4 is a side view of a glass cutter wheel where grooves areformed in an edge line portion of the wheel.

[0050]FIG. 5 is a side view of a glass cutter wheel of an embodiment ofthe present invention.

[0051]FIG. 6 is a side view of a glass cutter wheel of anotherembodiment of the present invention.

[0052]FIG. 7 shows a vertical crack formed when scribing is performedusing a glass cutter wheel of the present invention.

[0053]FIG. 8 illustrates a separation procedure using a scribingapparatus which incorporates a glass cutter wheel of the presentinvention.

[0054]FIG. 9 illustrates another separation procedure using a scribingapparatus which incorporates a glass cutter wheel of the presentinvention.

[0055]FIG. 10 is a side view showing a glass cutter wheel of Example 1.

[0056]FIG. 11 is a side view showing a glass cutter wheel of Example 2.

[0057]FIG. 12 is a side view showing a glass cutter wheel of Example 3.

[0058]FIG. 13 is a side view showing a glass cutter wheel of Example 4.

[0059]FIG. 14 is a side view showing a glass cutter wheel of Example 5.

[0060]FIG. 15 is a plan view showing a general structure of a glasscutter wheel production apparatus of embodiment 2.

[0061]FIG. 16 shows an example of a touch panel incorporated in amanipulation section of a glass cutter wheel production apparatus.

[0062]FIG. 17 is an example of a patrol light incorporated in a glasscutter wheel production apparatus.

[0063]FIG. 18 is a flowchart for illustrating steps of grinding processof a glass cutter wheel.

[0064]FIG. 19 is a front view of a scribing apparatus used in embodiment1.

[0065]FIG. 20 is a side view of a scribing apparatus used in embodiment1.

BEST MODE FOR CARRYING OUT THE INVENTION

[0066]FIG. 5 is a side view showing a glass cutter wheel 6 of embodiment1 of the present invention.

[0067] As shown in FIG. 5, this glass cutter wheel 6 has a region Awhere grooves are formed in a blade edge line portion and a region Bwhere grooves are not formed in the blade edge line portion.

[0068] The ratio of the edge line portion of the region A, where groovesare formed, with respect to the entire edge line portion (regionA+region B) (hereinafter, referred to as “the ratio of the region A tothe entire perimeter”) is preferably ¾ or less in view of theprocessibility for forming grooves in the edge line of the glass cutterwheel 6. With such a ratio, a process of forming grooves does not take along time, and good processibility can be obtained. In the case wherethe ratio of the region A to the entire perimeter is {fraction (3/)}4 orlower and higher than ¼, a vertical crack whose depth periodicallyvaries can be obtained as shown in FIG. 7 described later. In the casewhere the ratio of the region A to the entire perimeter is in such arange, it is necessary to impose limited conditions in order to obtainthe above periodical crack.

[0069] Alternatively, in the case where the ratio of the region A to theentire perimeter is ¼ or lower, a vertical crack whose depthperiodically varies can be stably obtained under broader conditions.Setting the ratio of the region A to the entire perimeter to be withinthis range is suitable for preventing a problem which may occur duringtransportation of a brittle substrate where a scribe line has beenformed, such as the dropping of a piece of the brittle substrate whichis separated during transportation.

[0070] The grooves 6 b formed in the region A of the edge line portionare intentionally formed on a periodic basis on the micron order. Thesegrooves 6 b should be considered to be different from abrasive streaksof the submicron order which are inevitably formed during a grindingprocess of forming a blade edge line.

[0071]FIG. 6 shows another example of a glass cutter wheel according toembodiment 1. In FIG. 6(a), the entire blade edge is divided into sixregions such that the regions A and the regions B are alternatelyformed. In FIG. 6(b), the entire blade edge is divided into eightregions such that the regions A and the regions B are alternatelyformed.

[0072] In FIG. 6(b), the regions A where grooves are formed are formedin a plurality of regions A1 through A4, and the regions B where groovesare not formed are formed in a plurality of regions B1 through B4. Thelength of each of the regions A1 through A4 and regions B1 through B4is, for example, set such that the following relationships aresatisfied:

[0073] A1=A2=A3=A4; A1+A2+A3+A4=A;

[0074] B1=B2=B3=B4; B1+B2+B3+B4=B; and

[0075] A/B=1.

[0076] In this case, the lengths of the regions A1 through A4 are allequal, and the lengths of the regions B1 through B4 are all equal.Further, since A/B=1 is satisfied, the ratio of the region A to theentire perimeter is {fraction (2/4)}.

[0077] In an alternative example, the following relationships aresatisfied:

[0078] A1=A2≠A3≠A4; A1+A2+A3+A4=A;

[0079] B1=B2≠B3≠B4; B1+B2+B3+B4=B; and

[0080] A/B=1.

[0081] In this case, as for the regions A1 through A4 and the regions B1through B4, the length of the region A3 and the length of the region A4are different from the length of the region A1 and the length of theregion A2, and the length of the region B3 and the length of the regionB4 are different from the length of the region B1 and the length of theregion B2. Further, as for the entire perimeter, since A/B=1 issatisfied, the ratio of the region A to the entire perimeter is{fraction (2/4)}.

[0082] In a further alternative example, the following relationships aresatisfied:

[0083] A1=A2≠A3≠A4; A1+A2+A3+A4=A;

[0084] B1=B2≠B3≠B4; B1+B2+B3+B4=B; and

[0085] A/B={fraction (3/1)}.

[0086] In this case, as for the regions A1 through A4 and the regions B1through B4, the length of the region A3 and the length of the region A4are different from the length of the region A1 and the length of theregion A2, and the length of the region B3 and the length of the regionB4 are different from the length of the region Bland the length of theregion B2. Further, as for the entire perimeter, since A/B={fraction(3/1)} is satisfied, the ratio of the region A to the entire perimeteris ¾.

[0087] This glass cutter wheel 6 may be formed integrally with a shaftwhich is inserted in the wheel 6. As a method for integrally forming theglass cutter wheel 6, a method of integrally grinding the wheel 6 andthe shaft, a method of attaching a blade edge and a shaft with anadhesive and/or by welding, etc., are employed.

[0088]FIG. 7 is a schematic view generally showing a vertical crackgenerated in a glass substrate when a scribe line is formed in the glasssubstrate using the above glass cutter wheel 6.

[0089] In a scribe line formed by scribing glass using the glass cutterwheel 6, the depth of a vertical crack is different in a scribe lineS_(A), which is formed by the region A having grooves, and in a scribeline S_(B), which is formed by the region B having no groove. In such ascribe line, a variation in the depth is found. That is, in the scribeline S_(A) a deep vertical crack D_(A) is formed due to the groovesformed in the edge line portion, whereas in the scribe line S_(B) ashallow vertical crack D_(B) is formed because grooves are not formed inthe edge line portion of the scribe line S_(B).

[0090] Thus, since the depth of the vertical crack periodically variesin the case of scribing performed using the glass cutter wheel 6 ofembodiment 1, the scribing ability of the glass cutter wheel 6 isbetween the scribing ability of the conventional glass cutter wheel 2 ofFIG. 2 and the scribing ability of the glass cutter wheel 5 of FIG. 4.Furthermore, by appropriately changing the ratio of the region A, wheregrooves are formed, and the region B, where grooves are not formed, withrespect to the entire perimeter of the glass cutter wheel, a desiredscribing characteristic can be obtained, i.e., a line of a desiredvertical crack for separating a glass substrate (scribe line) can beobtained.

[0091] Hereinafter, Examples 1-5 which illustrates specific examples ofthe glass cutter wheel of embodiment 1 are described.

EXAMPLE 1

[0092]FIG. 10 shows an embodiment of a glass cutter wheel of Example 1.TABLE 2 below shows dimensions of the glass cutter wheel of Example 1,such as a wheel diameter or the like. TABLE 2 Wheel diameter φ  2.0 mmWheel thickness w 0.65 mm Blade edge angle α 135° Depth of groove   7 μm

[0093] The glass cutter wheel 6 of Example 1 was designed such thatgrooves having identical depths (7 μm) are continuously formed over a{fraction (1/10)} portion (8 divisions/80 divisions) of the entireperimeter length of the edge line portion.

[0094] This glass cutter wheel 6 was used to scribe an alkali-free glassplate having a thickness of 0.7 mm with a blade edge load of 0.16 to0.40 MPa and at a scribing speed of 400 mm/s. In the scribing processusing the glass cutter wheel 6 of Example 1, a scribe line where thedepth of a vertical crack periodically varies was formed as shown inFIG. 7. In the case where a load of 0.18 MPa was used, the deep verticalcrack D_(A) shown in FIG. 7 was about 400 μm, and the shallow verticalcrack D_(B) shown in FIG. 7 was about 100 μM.

EXAMPLE 2

[0095]FIG. 11 shows an embodiment of a glass cutter wheel 6 of Example2. TABLE 3 below shows dimensions of the glass cutter wheel shown inFIG. 11, such as a wheel diameter or the like. TABLE 3 Wheel diameter φ 2.0 mm Wheel thickness w 0.65 mm Blade edge angle α 135° Depth ofgroove   7 μm

[0096] The glass cutter wheel 6 of Example 2 has regions A1 and A2 attwo separated positions in the perimeter of the glass cutter wheel 6,each of which is a 1/10 portion (8 divisions/80 divisions) of the entireperimeter length of the edge line portion, where grooves havingidentical depths (7 μm) are continuously formed. Regions A1 and A2,where grooves are formed, are provided at opposite sides of the glasscutter wheel 6 with respect to the central axis of the glass cutterwheel 6.

[0097] This glass cutter wheel 6 was used to scribe an alkali-free glassplate having a thickness of 0.7 mm with a blade edge load of 0.16 to0.40 MPa and at a scribing speed of 400 mm/s. In the scribing processusing the glass cutter wheel 6 of Example 2, a scribe line where thedepth of a vertical crack periodically varies was formed as shown inFIG. 7. In the case where a load of 0.20 MPa was used, the deep verticalcrack D_(A) shown in FIG. 7 was about 400 μm, and the shallow verticalcrack D_(B) shown in FIG. 7 was about 100 μm.

EXAMPLE 3

[0098]FIG. 12 shows an embodiment of a glass cutter wheel 6 of Example3. TABLE 4 below shows dimensions of the glass cutter wheel 6 of Example3, such as a wheel diameter or the like. TABLE 4 Wheel diameter φ  2.0mm Wheel thickness w 0.65 mm Blade edge angle α 135° Depth of groove   7μm

[0099] The glass cutter wheel 6 of Example 3 has regions A1, A2, and A3at three separated positions in the perimeter of the glass cutter wheel6, each of which is a {fraction (1/10)} portion (8 divisions/80divisions) of the entire perimeter length of the edge line portion,where grooves having identical depths (71 m) are continuously formed.Regions A1, A2, and A3 are provided at uniform intervals.

[0100] This glass cutter wheel 6 was used to scribe an alkali-free glassplate having a thickness of 0.7 mm with a blade edge load of 0.16 to0.40 MPa and at a scribing speed of 400 mm/s. In the scribing processusing the glass cutter wheel 6 of Example 3, a scribe line where thedepth of a vertical crack periodically varies was formed as shown inFIG. 7. In the case where a load of 0.20 MPa was used, the deep verticalcrack D_(A) shown in FIG. 7 was about 400 μm, and the shallow verticalcrack D_(B) shown in FIG. 7 was about 100 μm.

EXAMPLE 4

[0101]FIG. 13 shows an embodiment of a glass cutter wheel 6 of Example4. TABLE 5 below shows dimensions of the glass cutter wheel 6 of Example4, such as a wheel diameter or the like. TABLE 5 Wheel diameter φ  2.0mm Wheel thickness w 0.65 mm Blade edge angle α 135° Depth of groove 3,5, 7, 7, 7, 5, 3 μm

[0102] The glass cutter wheel 6 of Example 4 has region A at a positionin the perimeter of the glass cutter wheel 6, which is a {fraction(1/10)} portion (8 divisions/80 divisions) of the entire perimeterlength of the edge line portion. In region A, seven grooves are formed.These grooves are designed so as to have different depths, 3, 5, 7, 7,7, 5, 3 μm, in this order.

[0103] This glass cutter wheel 6 was used to scribe an alkali-free glassplate having a thickness of 0.7 mm with a blade edge load of 0.16 to0.40 MPa and at a scribing speed of 400 mm/s. In the scribing processusing the glass cutter wheel 6 of Example 4, a scribe line where thedepth of a vertical crack periodically varies was formed as shown inFIG. 7. In the case where a load of 0.22 MPa was used, the deep verticalcrack D_(A) shown in FIG. 7 was about 400 μm, and the shallow verticalcrack D_(B) shown in FIG. 7 was about 100 μm.

EXAMPLE 5

[0104]FIG. 14 shows an embodiment of a glass cutter wheel 6 of Example5. TABLE 6 below shows dimensions of the glass cutter wheel 6 of Example5, such as a wheel diameter or the like. TABLE 6 Wheel diameter φ  2.0mm Wheel thickness w 0.65 mm Blade edge angle α 140° Number of divisions106 Depth of groove 3, 5, 7, 7, 7, 5, 3 μm

[0105] In the glass cutter wheel 6 of Example 5, the entire perimeter ofthe edge line portion is divided into 106 divisions, such that grooveshaving lengths of 3, 5, 7, 7, 7, 5, and 3 μm are repeatedly formed inthis order along the entire perimeter.

[0106] This glass cutter wheel 6 was used to scribe an alkali-free glassplate having a thickness of 0.7 mm with a blade edge load of 0.16 to0.40 MPa and at a scribing speed of 400 mm/s. In the scribing processusing the glass cutter wheel 6 of Example 5, a scribe line where thedepth of a vertical crack periodically varies was formed as shown inFIG. 7. In the case where a load of 0.29 MPa was used, the deep verticalcrack D_(A) shown in FIG. 7 was about 400 μm, and the shallow verticalcrack D_(B) shown in FIG. 7 was about 100 μm.

[0107] From the above results of Examples 1-5, it was found that a pitchof the plurality of grooves continuously formed is preferably 20-200 μmaccording to the wheel diameter of 1-20 mm, and that the depth of theplurality of grooves is preferably 2-200 μm according to the wheeldiameter of 1-20 mm.

[0108] In the drawings used for illustrating the above-described cutterwheels of the present invention, the grooves formed at the edge line ofthe cutter wheel are shown in a large size for the purpose of readilyrecognizing the grooves. However, the actual size of the grooves is asize of the micron order, which is not perceptible by a human eye.

[0109] Next, a method for separating the bonded glass substrate 1 usinga separation apparatus which has the glass cutter wheel 6 of embodiment1 is described. The scribing apparatus used in the following descriptionis a scribing apparatus which has a mechanism for achieving a 0 rotationof a table, on which a glass plate is mounted, and for moving the tablealong the X-direction and/or Y-direction with respect to a cutter head.

[0110]FIGS. 19 and 20 show an example of a scribing apparatus, where atable performs a 0 rotation and moves along the Y-direction, and acutter head moves along the X-direction. FIG. 19 is a front view of thescribing apparatus, and FIG. 20 is a side view of the scribingapparatus.

[0111] As shown in FIGS. 19 and 20, this scribing apparatus has a table41 on which a glass plate is mounted. The table 41 is supported by arotation table 42 so as to be rotatable along a horizontal direction,and can be moved along the Y-direction (leftward/rightward directions inFIG. 19) by rotation of a ball screw 44. Furthermore, a cutter head 46,to which the above-described glass cutter wheel 11 of the presentinvention is rotatably attached such that the glass cutter wheel 11 isrotatable around its shaft, is movably supported along a rail 47 so asto be movable along the X-direction (leftward/rightward directions inFIG. 20).

[0112] In the case where scribing is performed using this scribingapparatus, the cutter head 46 is moved along the X-direction every timethe table 41 is moved along the Y-direction at a predetermined pitch,whereby a glass plate mounted on the table 41 is scribed along theX-direction. Thereafter, the table 41 is rotated by the rotation table42 by 90°, and scribing is performed in the same manner as describedabove, whereby a scribe line which crosses at right angles with thepreviously formed scribe line can be formed on the glass plate.

[0113] In the above scribing apparatus, reference numeral 43 denotes atable feed motor for moving the table 41 along the Y-direction;reference numeral 45 denotes a rail for supporting the rotation table 42such that the rotation table 42 is movable along the Y-direction;reference numeral 48 denotes a cutter shaft motor for rotating therotatably-supported glass cutter wheel 11; reference numerals 49 and 50denote CCD cameras for monitoring a glass substrate which is scribed onthe table 41; and reference numeral 51 denotes a camera supporting metalmember for supporting the CCD cameras 49 and 50.

[0114] FIGS. 8(a) through 8(c) are cross-sectional views whichillustrate a method for separating a bonded glass substrate 1 using aseparation apparatus which incorporates the glass cutter wheel 6 ofembodiment 1, in a step-by-step manner. In the following descriptions,in a bonded glass substrate formed by a pair of glass substrates, whichis a liquid crystal mother substrate, one of the glass substrates isreferred to as an A-side glass substrate, and the other glass substrateis referred to as a B-side glass substrate, for convenience ofexplanation.

[0115] (1) First, as shown in FIG. 8(a), the bonded glass substrate 1 isplaced on a first scribing apparatus such that the A-side glasssubstrate is laid over the B-side glass substrate, and the A-side glasssubstrate is scribed using the glass cutter wheel 5 so as to form ascribe line Sa. The first scribing apparatus uses the glass cutter wheel5 shown in FIG. 4 which has grooves along its entire perimeter. In thescribe line Sa formed using this glass cutter wheel 5, a deep verticalcrack which reaches the vicinity of the lower surface of the A-sideglass substrate, indicated by Va in the drawings, is formed.

[0116] (2) Next, the bonded glass substrate 1 where the scribe line Sawas formed in the A-side glass substrate is turned over, and transportedto a second scribing apparatus. In this second scribing apparatus, theB-side glass substrate of the bonded glass substrate 1 is scribed usingthe glass cutter wheel 6 so as to form a scribe line Sb which isparallel to the scribe line Sa as shown in FIG. 8(b). The secondscribing apparatus uses the glass cutter wheel 6 described in any ofExamples 1-5. In the scribe line Sb formed using this glass cutter wheel6, a vertical crack Vb which alternately includes shallow portions anddeep portions on a periodic basis is formed. It should be herein notedthat, in the case of a liquid crystal mother substrate, a plurality ofliquid crystal panels are formed from the liquid crystal mothersubstrate, and in each liquid crystal panel, it is necessary to formterminals at a side edge portion in one glass substrate. Thus, in manycases, the scribing position of the scribe line Sa formed in the A-sideglass substrate and the scribing position of the scribe line Sb formedin the B-side glass substrate are shifted from each other along ahorizontal direction.

[0117] (3) Next, the bonded glass substrate 1 where the scribe lines Saand Sb were formed in the A-side glass substrate and the B-side glasssubstrate, respectively, is turned over such that the A-side glasssubstrate is over the B-side glass substrate, and transported to abreaking apparatus. In this breaking apparatus, as shown in FIG. 8(c),the bonded glass substrate 1 is placed on a mat 4. A break bar 3 ispushed against the A-side glass substrate of the bonded glass substrate1 along the scribe line Sb formed in the B-side glass substrate. As aresult, in the lower B-side glass substrate, a crack extends upwardlyfrom the scribe line Sb, and accordingly, the B-side glass substrate isbroken along the scribe line Sb.

[0118] By sequentially performing above steps (1) through (3), thebonded glass substrate 1 is separated.

[0119] As previously described, in a scribing process using the glasscutter wheel 6 of the present invention, the vertical crack Vb whichalternately includes shallow portions and deep portions on a periodicbasis is formed, so that the vertical crack Vb does not thoroughlypenetrate through the glass substrate in the thickness directionthereof. Thus, even when the A-side glass substrate is completelyseparated during when the bonded glass substrate 1 is transported fromthe second scribing apparatus to the breaking apparatus at Step (2),there is no probability that the bonded glass substrate 1 is separatedbecause the A-side glass substrate is kept bonded to the B-side glasssubstrate.

[0120] FIGS. 9(a) through 9(d) are cross-sectional views forillustrating a second method for separating a bonded glass substrate 1using a separation apparatus which incorporates the glass cutter wheel 6of embodiment 1, in a step-by-step manner. In the followingdescriptions, in a bonded glass substrate formed by a pair of glasssubstrates, which is a liquid crystal mother substrate, one of the glasssubstrates is referred to as an A-side glass substrate, and the otherglass substrate is referred to as a B-side glass substrate, forconvenience of explanation.

[0121] (1) First, as shown in FIG. 9(a), the bonded glass substrate 1 isplaced on a first scribing apparatus such that the A-side glasssubstrate is laid over the B-side glass substrate, and the A-side glasssubstrate is scribed using the glass cutter wheel 2 so as to form ascribe line Sa. The vertical crack Va formed using this glass cutterwheel does not result in a deep vertical crack which reaches thevicinity of the lower surface of the glass substrate.

[0122] (2) Next, the bonded glass substrate 1 where the scribe line Sawas formed in the A-side glass substrate is turned over, and transportedto a first breaking apparatus. In this first breaking apparatus, asshown in FIG. 9(b), the bonded glass substrate 1 is placed on a mat 4. Abreak bar 3 is pushed against the B-side glass substrate of the bondedglass substrate 1 along the scribe line Sa formed in the A-side glasssubstrate. As a result, in the lower A-side glass substrate, a crackextends upwardly from the scribe line Sa, and accordingly, the A-sideglass substrate is broken along the scribe line Sa.

[0123] (3) Next, the bonded glass substrate 1 where the A-side glasssubstrate was separated is transported to a second scribing apparatuswithout being turned over, i.e., without exchanging the positions of theA-side glass substrate and the B-side glass substrate. In this secondscribing apparatus, the B-side glass substrate of the bonded glasssubstrate 1 is scribed using a glass cutter wheel 6 so as to form ascribe line Sb which is parallel to the scribe line Sa as shown in FIG.9(c). It should be herein noted that, in the case of a liquid crystalmother substrate, a plurality of liquid crystal panels are formed fromthe liquid crystal mother substrate, and in each liquid crystal panel,it is necessary to form terminals at a side edge portion in one glasssubstrate. Thus, in many cases, the scribing position of the scribe lineSb formed in the B-side glass substrate and the scribing position of thescribe line Sa formed in the A-side glass substrate are shifted fromeach other along a horizontal direction.

[0124] (4) Next, the resultant bonded glass substrate 1 is turned oversuch that the A-side glass substrate is over the B-side glass substrate,and transported to a second breaking apparatus. In this second breakingapparatus, as shown in FIG. 9(d), the bonded glass substrate is placedon a mat 4. The break bar 3 is pushed against the A-side glass substrateof the bonded glass substrate 1 along the scribe line Sb formed in theB-side glass substrate. As a result, in the lower B-side glasssubstrate, a crack extends upwardly from the scribe line Sb, andaccordingly, the B-side glass substrate is broken along the scribe lineSb. A vertical crack formed at the time of formation of the scribe lineSb in the B-side glass substrate at Step (3) is indicated by Vb in FIG.9(d).

[0125] As described above, in a scribing process using the glass cutterwheel 6 of the present invention, the vertical crack Vb whichalternately includes shallow portions and deep portions on a periodicbasis is formed, so that the vertical crack Vb does not thoroughlypenetrate through the glass substrate along the thickness directionthereof. Thus, even when the A-side glass substrate is completelyseparated during when the bonded glass substrate 1 is transported fromthe second scribing apparatus to the second breaking apparatus at Step(4), there is no probability that the bonded glass substrate 1 isseparated because the B-side glass substrate is not thoroughlyseparated.

[0126] In the above, the scribing methods for a bonded glass substratehave been described. As a special case, a different brittle material maybe scribed using the scribing method of the present invention. In thiscase also, a vertical crack which alternately includes shallow portionsand deep portions on a periodic basis can be formed in the differentbrittle material. By forming such a vertical crack having the depthwhich periodically varies, the brittle material can be transported to anext step without causing a thorough separation during transportation.

[0127] Next, a glass cutter wheel production apparatus for producing aglass cutter wheel where undulations are formed at a blade edge portionas shown in FIG. 5 is described.

[0128]FIG. 15 is a plan view showing a general structure of a glasscutter wheel production apparatus of embodiment 2 of the presentinvention.

[0129] This glass cutter wheel production apparatus 10 has a structurefor grinding an edge line portion of a blade edge of a glass cutterwheel so as to form grooves in the blade edge.

[0130] The glass cutter wheel production apparatus 10 has a housing 13in which a grindstone 12 rotatably supported by, and fixed to, a spindlemotor 11 is placed. In a front face of the housing 13, a door portion 14is provided which can be opened for introducing or removing a glasscutter wheel to be ground. The door portion 14 is used for a safetydoor, in which a safety control device (not shown) is provided forinterrupting a grinding step when the door is opened during grinding ofa glass cutter wheel.

[0131] Inside the housing 13, a grinding mechanism 15 is provided so asto advance toward and retract from the grindstone 12.Advancement/retraction of the grinding mechanism 15 toward/from thegrindstone 12 are achieved by a feeding motor 18. The feeding motor 18can adjust movement of the grinding mechanism 15 to and from a certainposition by rotating a ball screw (not shown).

[0132] The grinding mechanism 15 has a wheel supporting portion 19 forsupporting a glass cutter wheel during grinding. At a rear portion ofthe wheel supporting portion 19, a blade edge rotation motor 20 isprovided for rotating the glass cutter wheel by a preset angle.Furthermore, the grinding mechanism 15 has a handle 21 for alignment inthe horizontal direction and a handle 22 for alignment in the verticaldirection. With these handles, alignment in the horizontal and verticaldirections is adjusted manually, or automatically using a controlmechanism (not shown).

[0133] Outside the housing 13, a control device 25 for controlling theposition and operation of the grinding mechanism 15 is provided.Furthermore, the control device 25 has a manipulation section 26 fordesignating grinding conditions for grinding of a glass cutter wheel bythe grinding mechanism 15.

[0134] In the manipulation section 26, for example, a touch panel 30shown in FIG. 16 is provided. In the touch panel 30 which is shown as anexample in FIG. 16, a touch panel manipulation portion 31 is provided,on which various operation modes, set conditions, alarming, etc., forthe entire apparatus are displayed. In the lower part of the touch panel30, a power switch 32 for manipulating the power on and power of f of anoperational power source, an illumination-type push button switch 33 fordesignating start of operation preparation, a warning buzzer 34 foremitting warning information, and an emergency stop push button switch35 for providing an instruction to stop the operation in an emergencyare provided.

[0135] Furthermore, a signal tower 40 is provided on the housing 13. Thesignal tower 40 is an indication light which indicates the status of theinside of the housing, e.g., an abnormality has occurred, the apparatusis in automatic operation, there is no problem in opening/closing thedoor, etc. FIG. 17 shows an example of the signal tower 40. In thisexample, there are provided a “red” indication light 41 which indicatesthat an abnormality has occurred in the housing 13, a “green” indicationlight 42 which indicates that the operation performed inside the housing13 is automatic, and a “yellow” indication light 43 which indicates thatthere is no problem in opening/closing the door.

[0136] Next, an operation of the glass cutter wheel production apparatus10 having the above structure is described.

[0137] First, the manipulation section 26 is manipulated to performinitial setting of grinding conditions for a glass cutter wheel to beground.

[0138] In this initial setting, for example, the following conditionsare input:

[0139] Rotation angle number ratio F₁ in the first region; depth ofgroove, D₁₁, . . . , D_(1n)

[0140] Rotation angle number ratio F₂ in the second region; depth ofgroove, D₂₁, . . . , D_(2n)

[0141] Rotation angle number ratio F_(m) in the m-th region; depth ofgroove, D_(m1), . . . , D_(mn)

[0142] Number of loops: L

[0143] Number of divisions in one region: N

[0144] Depth of groove: D1, D2, . . . , Dn

[0145] Number of region: R

[0146] After the initial settings have been input, a step of grinding aglass cutter wheel is begun. FIG. 18 is a flowchart which illustratesthe step of grinding a glass cutter wheel. Hereinafter, the step ofgrinding a glass cutter wheel is described based on this flowchart.

[0147] First, at Step 1, the number of divisions is set to 0 (n=0), andthen at Step 2, the number of regions is set to 1 (r=1).

[0148] Next, at Step 3, a glass cutter wheel to be ground is attached tothe wheel supporting portion 19.

[0149] Next, the manipulation section 26 is manipulated to start anautomatic operation of the grinding mechanism 15.

[0150] Next, a position where a tip of the grindstone 12 comes intocontact with a blade edge of the glass cutter wheel is detected. Indetection of the contact position, optical means, mechanical means, orelectrical means may be used. Detection of a contact of the blade edgeof the glass cutter wheel with the grindstone 12 is performed every timethe blade edge comes into contact with the grindstone 12.

[0151] When a position where the tip of the grindstone 12 comes intocontact with the blade edge is detected, the grinding mechanism 15 ismoved back to a standby position by the feeding motor 18 at Step 6.

[0152] Next, at Step 7, the blade edge rotation motor 20 is rotated sothat the glass cutter wheel supported by the wheel supporting portion 19by a predetermined angle.

[0153] Next, at Step 8, the number of division, n, is updated to (n+1)by adding 1 to n.

[0154] Next, at Step 9, the grinding mechanism 15 is moved toward thegrindstone 12 such that the blade edge comes in contact with thegrindstone 12, and that the n-th groove is processed so as to have thedepth of Dmn.

[0155] At Step 9, grooves are formed such that the n-th groove in them-th region R has depth Dmn, which corresponds to an input valuepreviously set in the above-described initial setting step. Similarly,the rotation angle number in the m-th region R is previously set basedon the rotation angle number ratio F_(m) in the m-th region, which is aninput value set in the above-described initial setting step, forformation of the grooves.

[0156] Next, at Step 10, the grinding mechanism 15 is moved to thestandby positions.

[0157] Next, at Step 11, the number of divisions n and the number ofdivisions N are compared to examine whether or not n<N is satisfied. Ifn<N is satisfied, the process proceeds to Step 12. If n<N is notsatisfied, the process proceeds to Step 13.

[0158] When it is confirmed that n<N is satisfied, and the processproceeds to Step 12, the blade edge rotation motor 20 is rotated by avery small angle at Step 12. Then, the process returns to Step 6, andgrinding processing is performed at a position of the blade edge rotatedby the very small angle.

[0159] When it is confirmed at Step 11 that n<N is not satisfied, thismeans that when the number of divisions n has already reached the numberof divisions N, the process proceeds to Step 13, and it is examined atStep 13 whether or not r<R is satisfied.

[0160] When it is confirmed at Step 13 that r<R is satisfied, theprocess proceeds to Step 14. At Step 14, the blade edge is rotated bythe blade edge rotation motor 20 by a set angle.

[0161] Subsequently, the process proceeds to Step 15. At Step 15, theset number of regions, r, is updated to (r+1) by adding 1. After updateof the number of regions at Step 15, the process returns to Step 6, andthe grinding processing is again performed.

[0162] When it is confirmed at Step 13 that r<R is not satisfied, thismeans that when the number of regions r has already reached theinitially-set number of regions R, the process proceeds to Step 16, andthe grinding mechanism 15 is moved back to their original positions.

[0163] Next, at Step 17, the glass cutter where the blade edge has beenground is removed, and the grinding process terminates.

[0164] By using the above-described glass cutter wheel productionapparatus 10 of embodiment 2, a groove having a desired depth can beformed at a desired position of the entire perimeter of a blade edgewith satisfactory accuracy.

[0165] In the cutter wheel production apparatus shown in FIG. 15, onegrinding mechanism 15 is provided for the grindstone 12. However, astructure where a grindstone is positioned at about the center of thehousing, and a plurality of grinding mechanisms are provided such thatthe grindstone is surrounded by the grinding mechanisms, may beemployed. With such a structure, the processing efficiency of a cutterwheel can be significantly increased relative to the number of thegrinding mechanisms provided.

[0166] Alternatively, a plurality of grindstones may be vertically piledup and arranged such that blade edges of a plurality of cutter wheelsface the respective grindstones. Alternatively, a structure where aplurality of cutter wheels can be attached to one cutter wheelsupporting portion of a grinding mechanism, and the plurality of cutterwheels can be ground simultaneously in one grinding step, may beemployed. With such a structure, the processing efficiency of a cutterwheel can be significantly increased.

INDUSTRIAL APPLICABILITY

[0167] As described above, according to the present invention, in aglass cutter wheel where a blade edge is formed in a disk-shaped wheel,grooves having a predetermined shape are formed at a predetermined pitchin ¾ or less of the blade edge line portion of the entire perimeter ofthe blade edge. Such a glass cutter wheel has good processibility incomparison to a glass cutter wheel where grooves are formed over theentire perimeter of the blade edge.

[0168] Another glass cutter wheel where grooves are formed at apredetermined pitch in ¼ or less portion of the entire perimeter of theblade edge can prevent formation of a vertical crack which reaches thevicinity of a lower surface of a substrate. By changing the ratio ofgrooves with respect to the entire perimeter length, a desired scribingcharacteristic can be obtained. Thus, by changing the scribingcharacteristic, separation of a glass substrate at a scribe lineposition and the dropping of the separated glass substrate, which mayoccur during transportation of the glass substrate, can be obviated.

1. A scribing method using a brittle material separation disk-shapedwheel having a central portion in a thickness direction protruding in acircumferential direction so as to form a blade edge at an edge lineportion of the wheel, and a plurality of grooves having a predeterminedshape formed in the edge line portion at a predetermined pitch, whereinscribing is performed using a wheel where the ratio of a length of aregion occupied by the plurality of grooves with respect to an entireperimeter of the edge line portion is smaller than 1, whereby a depth ofa vertical crack formed inside a scribed brittle material isperiodically varied.
 2. A scribing method according to claim 1, whereinscribing is performed using a wheel where the ratio of a length of aregion occupied by the plurality of grooves with respect to the entireperimeter of the edge line portion is equal to or smaller than ¾.
 3. Ascribing method according to claim 1, wherein scribing is performedusing a wheel where the ratio of a length of a region occupied by theplurality of grooves with respect to the entire perimeter of the edgeline portion is equal to or smaller than ¼.
 4. A cutter wheel used forseparating a brittle material, where a blade edge is formed in an edgeline portion of a disk-shaped wheel, and a plurality of grooves having apredetermined shape are formed in the edge line portion at apredetermined pitch, wherein the ratio of a length of a region occupiedby the plurality of grooves with respect to an entire perimeter of theedge line portion is smaller than
 1. 5. A cutter wheel according toclaim 4, wherein the ratio of a length of a region occupied by theplurality of grooves with respect to the entire perimeter of the edgeline portion is greater than ¼, and equal to or smaller than ¾.
 6. Acutter wheel according to claim 4, wherein the ratio of a length of aregion occupied by the plurality of grooves with respect to the entireperimeter of the edge line portion is equal to or smaller than ¼.
 7. Acutter wheel according to any of claims 4 to 6, wherein the pitch atwhich the plurality of grooves are formed is 20-200 μm according to awheel diameter of 1-20 mm.
 8. A cutter wheel according to any of claims4 to 6, wherein the depth of the plurality of grooves is 2-200 μmaccording to a wheel diameter of 1-20 mm.
 9. A cutter wheel according toany of claims 4 to 8, wherein the cutter wheel is integrally formed witha shaft which penetrates through the wheel.
 10. A cutter wheel accordingto any of claims 4 to 6, wherein: at least one groove region is formedin the edge line portion; and the grooves have different depths suchthat the depth of the groove is deeper in a central portion of thegroove region than in end portions of the groove region.
 11. A cutterwheel, wherein: groove regions are formed over the entire perimeter ofthe edge line portion; and a region where the depth of the groovesbecomes deeper, and a region where the depth of the grooves becomesshallower, are continuously provided.
 12. A scribing apparatus includinga mechanism for moving a cutter head along the X-direction and/or theY-direction with respect to a table on which a brittle material isplaced, wherein the cutter head is provided with the cutter wheel of anyof claims 4 to
 11. 13. A method for separating a bonded glass substrate,comprising a first scribing step, a second scribing step, and a breakingstep, wherein the glass cutter wheel of any of claims 4 to 11 is used inthe second scribing step.
 14. A method for separating a bonded glasssubstrate, comprising a first scribing step, a first breaking step, asecond scribing step, and a second breaking step, wherein the glasscutter wheel of any of claims 4 to 11 is used in the second scribingstep.
 15. A cutter wheel production apparatus for producing the cutterwheel of any of claims 4 to 11, comprising: at least one rotatablysupported disk-shaped grinding member; and a grinding mechanism whichsupports at least one cutter wheel to be ground, and which advances andretracts the cutter wheel toward/from the grinding member, wherein thegrinding mechanism has rotation means for moving a portion of the cutterwheel which is to be ground by the grinding member.
 16. A cutter wheelproduction apparatus according to claim 15, further comprising:advancing/retracting means for advancing/retracting the grindingmechanism toward/from the grinding member; and control means forcontrolling the advancing/retracting means and the rotation means.
 17. Acutter wheel production apparatus according to claim 16, wherein thecontrol means controls the rotation means based on the number ofdivisions and number of regions over the entire perimeter of an edgeline portion of the cutter wheel, so as to form a groove at a desiredposition in the edge line portion.